Atlantic oceanic route
By reference to [figure 17] it will be noted that route No. 1 is almost entirely oceanic, passing directly over the Atlantic Ocean from Labrador and Nova Scotia to the Lesser Antilles, and then through this group of small islands to the mainland of South America. This is not a popular route and its chief claim to fame is that it is the fall route used by most of the adult eastern golden plovers, and probably by some other shore birds. Since it lies entirely over the sea, this route is definitely known only at its terminals and from occasional observations made on Bermuda and other islands in its course. Some of the shore birds that breed on the Arctic tundra of Mackenzie and Alaska fly southeastward across Canada to the Atlantic coast and finally follow this oceanic route to the mainland of South America. The golden plover may accomplish the whole 2,400 miles without pause or rest, in fair weather the flocks passing Bermuda and sometimes even the islands of the Antilles without stopping. Although most birds make their migratory flights either by day or by night, the golden plover in this remarkable journey flies both day and night. As it swims lightly and easily it may make a few short stops along the way, and it has been seen actually resting on the ocean. Other shore birds have been observed busily feeding in the great area of ocean known as the Sargasso Sea, where thousands of square miles of floating seaweed teem with marine life.
Figure 14.—The Mississippi flyway.
Figure 15.—The Central flyway.
Figure 16.—The Pacific flyway.
The annual flight of the adult eastern golden plover is so wonderful that it may be given in some detail, particularly since it is one of the exceptions to the general rule that spring and fall movements are over the same routes ([fig. 18]). After reaching the South American coast the birds make a short stop and then continue overland to the pampas of Argentina, where they remain from September to March. Leaving their winter quarters, they cross northwestern South America and the Gulf of Mexico, reaching the North American mainland on the coasts of Texas and Louisiana. Thence they proceed slowly up the Mississippi Valley, and by the early part of June are again on their breeding grounds, having performed a round-trip journey in the form of an enormous ellipse with the minor axis about 2,000 miles and the major axis 8,000 miles, reaching from the Arctic tundra to the pampas of Argentina. The older birds are probably accompanied by some of the young, perhaps those from early nestings, but most of the immature birds leave their natal grounds late in summer and move southward through the interior of the country, returning in spring over essentially the same course. The elliptical route is therefore used chiefly by fully adult birds.
Figure 17.—Principal migration routes used by birds in passing from North America to winter quarters in the West Indies, Central America, and South America. Route No. 4 is the one used most extensively; only a few species make the 2,400-mile flight from Nova Scotia to South America.
Figure 18.—Distribution and migration of the golden plover. Adults of the eastern form migrate across northeastern Canada and then by a nonstop flight reach South America. In spring they return by way of the Mississippi Valley. Their entire route is therefore in the form of a great ellipse with a major axis of 8,000 miles and a minor axis of about 2,000 miles. The Pacific golden plover, which breeds in Alaska, apparently makes a nonstop flight across the ocean to Hawaii, the Marquesas Islands, and the Low Archipelago, returning in spring over the same route.